This invention relates to a paper feeder used in printers and the like.
Paper feeders hitherto known are configured such that sheets stored in a sheet-feeding cassette in a piled state are taken out by a pickup roller one at a time, sent to a feed roller, and conveyed to a printing position. However, since the sheets are piled on each other, there exists the possibility of two or more sheets being taken out by the pickup roller. In view of such circumstances, a mechanism has been proposed to reliably convey only one sheet through a feed roller, the feed roller being held in resilient contact with a retard roller such that a second and further sheets are backed by the retard roller (see, for example, U.S. Pat. No. 4,368,881).
According to the foregoing prior art, the driving power for driving a retard roller is provided by the driving motor for driving a sensitizing drum of the printer; thus, a large number of parts, such as electromagnetic clutch and gear train, are required to transfer the turning force from the driving motor to the retard roller. Further, the retard roller must be brought into resilient contact with a feed roller with a given pressure to convey only one sheet. Therefore, the structure is complicated and the costs are high.